Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
  • D21C9/001—Modification of pulp properties
  • D21C9/002—Modification of pulp properties by chemical means; preparation of dewatered pulp, e.g. in sheet or bulk form, containing special additives
  • D21C9/005—Modification of pulp properties by chemical means; preparation of dewatered pulp, e.g. in sheet or bulk form, containing special additives organic compounds
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C5/00—Other processes for obtaining cellulose, e.g. cooking cotton linters ; Processes characterised by the choice of cellulose-containing starting materials
  • D21C5/005—Treatment of cellulose-containing material with microorganisms or enzymes
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
  • D21H11/16—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only modified by a particular after-treatment
  • D21H11/20—Chemically or biochemically modified fibres
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
  • D21H11/12—Pulp from non-woody plants or crops, e.g. cotton, flax, straw, bagasse
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/005—Microorganisms or enzymes
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/03—Non-macromolecular organic compounds
  • D21H17/05—Non-macromolecular organic compounds containing elements other than carbon and hydrogen only
  • D21H17/06—Alcohols; Phenols; Ethers; Aldehydes; Ketones; Acetals; Ketals
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/03—Non-macromolecular organic compounds
  • D21H17/05—Non-macromolecular organic compounds containing elements other than carbon and hydrogen only
  • D21H17/14—Carboxylic acids; Derivatives thereof

Definitions

• the present invention provides a process for modifying a lignocellulosic material, notably in fibre form (e.g. vegetable fibres originating from wood, flax, hemp, jute, bagasse and the like) so as to increase the binding capacity thereof with respect to binding of ionically charged strengthening agents, and thereby make possible the preparation of lignocellulose-based products (such as paper, paperboard, cardboard, linerboard, corrugated board, unbleached board and like products, sometimes referred to in the present specification simply as "paper products”) of enhanced strength.
• lignocellulose-based products such as paper, paperboard, cardboard, linerboard, corrugated board, unbleached board and like products, sometimes referred to in the present specification simply as "paper products"
• Lignocellulose-based products prepared from lignocellulosic starting materials including products manufactured starting from vegetable fibre (e.g. wood fibre) prepared by mechanical (e.g. thermomechanical) pulping procedures, mechanical/-chemical pulping procedures (the latter often being denoted “semi-chemical” procedures) or chemical pulping procedures (such as kraft, sulfite or soda pulping), are indispensable everyday materials.
• vegetable fibre e.g. wood fibre
• mechanical/-chemical pulping procedures the latter often being denoted "semi-chemical” procedures
• chemical pulping procedures such as kraft, sulfite or soda pulping
• EP 0 433 258 A1 discloses a procedure for the production of mechanical pulp from a fibrous product using a chemical and/or enzymatic treatment in which a "binding agent" is linked with the lignin in the fibrous product via the formation of radicals on the lignin part of the fibrous product.
• a binding agent such as cationic starch, and/or proteins as examples of suitable binding agents.
• suitable enzymes laccase, lignin peroxidase and manganese peroxidase, and as examples of suitable chemical agents are mentioned hydrogen peroxide with ferro ions, chlorine dioxide, ozone, and mixtures thereof.
• EP 0 565 109 A1 discloses a method for achieving binding of mechanically produced wood fragments via activation of the lignin in the middle lamella of the wood cells by incubation with phenol-oxidizing enzymes. The use of a separate binder is thus avoided by this method.
• WO 92/20857 describes a process for inter alia the removal of lignin from lignocellulose-containing material.
• the process uses laccase enzymes as well as non-aromatic redox agents as well as phenolic and/or non-phenolic aromatic redox compounds.
• WO 88/03190 discloses a process for transforming and/or extracting lignin or its decomposition products from lignin-cellulosic materials.
• the redox potential is controlled by adding oxidizing and/or reducing agents and/or salts and/or phenolic compounds to an acidic aqueous solution of the lignin-containing ra-materials.
• the reaction is then initiated by addition of enzymes, microorganisms, animal or vegetable cells.
• WO 95/07604 describes a method for producing fiberboard comprising treating the lignin-containing wood material with a phenol oxidizing enzyme system, forming the fiber slurry into a mat, and pressing the formed mat to a fiberboard by application of heat and pressure.
• US 4,432,921 describes a process for producing a binder for wood products from a phenolic compound having phenolic groups, and the process in question involves treating the phenolic compound with enzymes to activate and oxidatively polymerize the phenolic compound, thereby converting it into the binder.
• cationic starches i.e. starches which have been modified by the introduction of cationic functionalities, normally quaternary ammonium groups.
• Cationic starches of the quaternary ammonium type are widely used in the industry as so-called "wet-end additives" for improving, inter alia , strength and drainage, and as binders in coatings.
• Other types of cationic agents which are commercially available for use as strengthening agents include cationic derivatives of guar gum [a poly(galactomannan) gum].
• such substances are able to bind relatively strongly, presumably via substantially electrostatic interaction, with oppositely charged functionalities [such as deprotonated carboxyl groups of uronic acid (e.g. glucuronic acid) moieties, or sulfonate groups originating from chemical modification of lignin] present in/on the fibres in lignocellulosic fibre pulp.
• functionalities such as deprotonated carboxyl groups of uronic acid (e.g. glucuronic acid) moieties, or sulfonate groups originating from chemical modification of lignin
• the increase in strength achievable in this manner is determined by, inter alia, the "density" of appropriately charged groups on the surface of the fibres.
• the present inventors have now surprisingly found that it is possible, by means of a straightforward procedure employing an enzyme which catalyzes the oxidation of phenolic groups (such as an oxidase classified under EC 1.10.3), in the presence of an appropriate oxidizing agent, to attach to a lignocellulosic material (such as wood fibres or other vegetable fibres) a phenolic carboxylic acid or a salt or an ester thereof which, in the attached form of the phenolic carboxylic acid or a salt or an ester thereof is, or under suitable conditions becomes, negatively charged.
• an enzyme which catalyzes the oxidation of phenolic groups (such as an oxidase classified under EC 1.10.3), in the presence of an appropriate oxidizing agent, to attach to a lignocellulosic material (such as wood fibres or other vegetable fibres) a phenolic carboxylic acid or a salt or an ester thereof which, in the attached form of the phenolic carboxylic acid or
• the phenolic carboxylic acids or salts or esters thereof in question are preferably substances of relatively low molecular weight; thus, in general, non-polymeric phenolic carboxylic acids are preferred ( vide infra ).
• Phenolic polysaccharides i.e. polysaccharides which are substituted with substituents containing a phenolic hydroxy group
• the phenolic polysaccharides employed in the context of the invention which is disclosed in applicant's International application No. PCT/DK95/00318 are not within the scope of phenolic carboxylic acids or salts or esters thereof employed in accordance with the present invention.
• the present invention thus provides a process for the production of a lignocellulosic material modified by attachment thereto of a phenolic carboxylic acid or salt or ester thereof which, in the attached form of the phenolic carboxylic acid or salt or ester thereof, is, or under suitable conditions (e.g. conditions resulting in protonation or deprotonation of the substituent in question) becomes, negatively charged.
• a lignocellulosic material and the phenolic carboxylic acid or salt or ester thereof in question are both subjected to an oxidation reaction brought about by the presence of an appropriate oxidizing agent and enzyme capable of catalyzing the oxidation of phenolic groups by that oxidizing agent.
• the oxidation products of the lignocellulosic material and the phenolic carboxylic acid or salt or ester thereof (which, as described below, are believed to be radical species) are then allowed to react with each other so as to form the modified lignocellulosic material in question.
• Enzymes of the type(s) employed in the process of the present invention i.e. enzymes capable of catalyzing the oxidation of phenolic groups, are believed to lead to formation, in the presence of an appropriate oxidizing agent, of radicals in the aromatic moieties of phenolic substituents (such as, on the one hand, phenolic functionalities in phenolic carboxylic acids as employed in the process of the invention, and, on the other hand, phenolic functionalities in the lignin part of a lignocellulosic substrate). Irrespective of its exact nature, the reaction in question may appropriately be termed "activation".
• the order of mixing/contacting the four components i.e. the lignocellulosic material, the phenolic carboxylic acid, the enzyme and the oxidizing agent, is not critical as long as the process set-up ensures that the "activated” lignocellulosic material and the "activated” phenolic carboxylic acid are brought together in a way that enables them to react in the desired manner. It is thus possible to perform the process of the invention in one or more steps or stages, for example as follows:
• a reaction medium in which a process of the invention (or a step or stage thereof) as disclosed above is performed will be a predominantly aqueous medium.
• the medium may - in addition to the above-mentioned components - contain, for example, a pH-adjusting agent (acid, base and/or buffering agent), one or more water-miscible organic solvents (e.g. to assist in solubilization of the phenolic carboxylic acid in question) and/or other appropriate adjuvants.
• lignocellulosic material as employed herein is intended to embrace naturally occurring, synthetic and semi-synthetic materials having (i) a cellulosic or hemicellulosic part and (ii) a lignin or lignin-like part.
• a cellulosic material such as cotton (which itself contains little or no lignin) which has been chemically modified so as to introduce a lignin-like (e.g. phenolic) component is to be understood as being a lignocellulosic material in the context of the invention.
• the lignocellulosic starting material employed in the process of the invention can be in any appropriate form, e.g. in the form of vegetable fibre pulp (containing fibres from wood, flax, hemp, bagasse, jute or the like), depending on the type of product to be manufactured.
• Fibre pulp suitable for use in the process of the invention may be produced by a variety of conventional pulping procedures, such as mechanical (e.g. thermomechanical) pulping procedures, mechanical/chemical pulping procedures (the latter often being denoted "semi-chemical” procedures) or chemical pulping procedures (such as kraft, sulfite or soda pulping). Pulp produced by a chemical pulping procedure may be bleached or unbleached.
• lignocellulosic material in question in an amount corresponding to a weight percentage of dry lignocellulosic material [dry substance (DS)] in the medium in the range of 0.01-90%, such as 0.1-40% w/w.
• phenolic carboxylic acids include phenolic carboxylic acids and derivatives thereof wherein the carboxyl group is esterified (e.g. with a lower alkyl group) or is in the salt form (-COO - ).
• a relatively water-soluble salt form such as the sodium salt or another alkali metal salt (produced, for example, in situ by dissolving the acid in an aqueous solution of the appropriate base, e.g. NaOH)].
• a phenolic substance employed in the context of the invention may optionally further be substituted in the same aromatic ring with one or more other substituents, e.g. one or more lower alkoxy groups (such as methoxy, ethoxy, 1-propoxy or 2-propoxy), and/or one or more lower alkyl groups (such as methyl, ethyl, 1-propyl or 2-propyl).
• substituents e.g. one or more lower alkoxy groups (such as methoxy, ethoxy, 1-propoxy or 2-propoxy), and/or one or more lower alkyl groups (such as methyl, ethyl, 1-propyl or 2-propyl).
• phenolic carboxylic acids examples include phenolic derivatives of benzoic acid, e.g. 2-, 3- or 4-hydroxybenzoic acid (particularly 4-hydroxybenzoic acid), vanillic acid (i.e. 4-hydroxy-3-methoxybenzoic acid) and syringic acid (i.e. 4-hydroxy-3,5-dimethoxybenzoic acid).
• phenolic carboxylic acids include phenolic derivatives of cinnamic acid, such as the coumaric acids (particularly p-coumaric acid, i.e. 4-hydroxycinnamic acid), caffeic acid (3,4-dihydroxycinnamic acid), sinapinic acid (3,5-dimethoxy-4-hydroxycinnamic acid; also known as sinapic acid) and ferulic acid (4-hydroxy-3-methoxycinnamic acid).
• coumaric acids particularly p-coumaric acid, i.e. 4-hydroxycinnamic acid
• caffeic acid (3,4-dihydroxycinnamic acid)
• sinapinic acid (3,5-dimethoxy-4-hydroxycinnamic acid; also known as sinapic acid
• ferulic acid (4-hydroxy-3-methoxycinnamic acid).
• cinnamic acid derivatives such as those specifically mentioned above (all of which are commercially available), it does not appear to have been established clearly whether they comprise one or both of the two possible geometric isomeric forms ( cis and trans, respectively), or both; it appears likely, however, that the trans form is generally predominant.
• the amount of phenolic carboxylic acid employed in the process of the invention will generally be in the range of 0.01-20 weight per cent (%w/w), typically 0.01-10 % w/w, based on the weight of lignocellulosic material (calculated as dry lignocellulosic material), and amounts in the range of about 0.02-6 % w/w (calculated in this manner) will often be very suitable.
• Enzyme classification numbers (EC numbers) referred to in the present specification with claims are in accordance with the Recommendations (1992) of the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology, Academic Press Inc., 1992.
• any type of enzyme capable of catalyzing oxidation of phenolic groups may be employed in the process of the invention.
• Preferred enzymes are, however, oxidases, particularly oxidases classified under EC 1.10.3 [e.g. laccases (EC 1.10.3.2)] and peroxidases (EC 1.11.1.7), particularly peroxidases classified under EC 1.11.1.7. In some cases it may be appropriate to employ two or more different enzymes in the process of the invention.
• Oxidases As mentioned above, preferred oxidases in the context of the present invention are oxidases classified under EC 1.10.3, which are oxidases capable of catalyzing oxidation of phenolic groups. Oxidases are enzymes employing molecular oxygen as acceptor (i.e. enzymes catalyzing oxidation reactions in which molecular oxygen functions as oxidizing agent).
• laccases are very suitable oxidases in the context of the invention.
• examples of other potentially useful, phenol-oxidizing oxidases in the context of the invention include the catechol oxidases (EC 1.10.3.1).
• villosus Coriolus pinsitus ], Polyporus, Rhizoctonia (e.g. R. solani ), Coprinus (e.g. C. plicatilis ), Psatyrella, Myceliophthora (e.g. M. thermophila ) , Schytalidium, Phlebia (e.g. P. radita; see WO 92/01046), or Coriolus (e.g. C.hirsutus; see JP 2-238885).
• laccases in the context of the invention include laccase obtainable from Trametes villosa and laccase obtainable from Myceliophthora thermophila.
• the amount of laccase employed in the process of the invention should generally be in the range of 0.02-2000 LACU per g (dry weight) of lignocellulosic material, preferably 0.05-100 LACU/g of lignocellulosic material, and will typically be in the range of 0.1-100 LACU/g, such as about 1 LACU/g, of lignocellulosic material (LACU is the unit of laccase activity as defined below).
• Laccase activity as defined herein is determined on the basis of spectrophotometric measurements of the oxidation of syringaldazin under aerobic conditions. The intensity of the violet colour produced in the oxidation reaction is measured at 530 nm.
• the analytical conditions are: 19 ⁇ M syringaldazin, 23.2 mM acetate buffer, pH 5.5, 30°C, reaction time 1 minute, shaking.
• 1 laccase unit (LACU) is the amount of enzyme that catalyses the conversion of 1 ⁇ M of syringaldazin per minute under these conditions.
• the amount of laccase employed in the process of the invention will generally be in the range of 0.0001-20 mg of laccase (calculated as pure enzyme protein) per gram (dry weight) of lignocellulosic material, such as 0.0001-10 mg/g, more usually 0.001-1 mg/g, and will typically be in the range of 0.01-1 mg of laccase per gram of lignocellulosic material.
• Peroxidases employed in the process of the invention are preferably peroxidases obtainable from plants (e.g. horseradish peroxidase or soy bean peroxidase) or from microorganisms, such as fungi or bacteria.
• plants e.g. horseradish peroxidase or soy bean peroxidase
• microorganisms such as fungi or bacteria.
• some preferred fungi include strains belonging to the subdivision Deuteromycotina, class Hyphomycetes, e.g.
• fungi include strains belonging to the subdivision Basidiomycotina, class Basidiomycetes, e.g. Coprinus, Phanerochaete, Coriolus or Trametes, in particular Coprinus cinereus f. microsporus (IFO 8371), Coprinus macrorhizus, Phanerochaete chrysosporium (e.g. NA-12) or Trametes versicolor (e.g. PR4 28-A).
• Basidiomycotina class Basidiomycetes
• Coprinus cinereus f. microsporus IFO 8371
• Coprinus macrorhizus e.g. NA-12
• Trametes versicolor e.g. PR4 28-A
• fungi include strains belonging to the subdivision Zygomycotina, class Mycoraceae, e.g. Rhizopus or Mucor, in particular Mucor hiemalis .
• Some preferred bacteria include strains of the order Actino-mycetales, e.g. Streptomyces spheroides (ATTC 23965), Streptomyces thermoviolaceus (IFO 12382) or Streptoverticillum verticillium ssp. verticillium.
• Bacillus pumilus ATCC 12905
• Bacillus stearothermophilus Rhodobacter sphaeroides
• Rhodomonas palustri Rhodomonas palustri
• Streptococcus lactis Pseudomonas purrocinia
• Pseudomonas fluorescens NRRL B-11.
• bacteria include strains belonging to Myxococcus, e.g. M. virescens.
• preferred peroxidases in the context of the invention include peroxidases classified under EC 1.11.1.7.
• an amount thereof in the range of 0.00001-1 mg of peroxidase (calculated as pure enzyme protein) per gram (dry weight) of lignocellulosic material such as 0.00001-0.1 mg/g, will generally be appropriate.
• the amount employed will often be in the range of 0.0001-0.1 mg/g, e.g. in the range of 0.0001-0.01 mg of peroxidase per gram of lignocellulosic material.
• the enzyme(s) and oxidizing agent(s) used in the process of the invention should clearly be matched to one another, and it is clearly preferable that the oxidizing agent (s) in question participate(s) only in the oxidative reaction involved in the binding process, and does/do not otherwise have any adverse effect on the substances/materials involved in the process.
• Oxidases of the types in question are, among other reasons, well suited in the context of the invention since - as mentioned above - they catalyze oxidation by molecular oxygen.
• reactions taking place in vessels open to the atmosphere and involving an oxidase as enzyme will be able to utilize atmospheric oxygen as oxidant; it may, however, be desirable to forcibly aerate the reaction medium with air or another oxygen-containing gas (e.g. oxygen-enriched air or, if appropriate, substantially pure oxygen) during the reaction to ensure an adequate supply of oxygen.
• oxygen-containing gas e.g. oxygen-enriched air or, if appropriate, substantially pure oxygen
• hydrogen peroxide is a preferred peroxide (oxidizing agent) in the context of the invention and is normally employed in a concentration (in the reaction medium) in the range of 0.01-500 mM, typically in the range of 0.01-100 mM.
• concentration range will be from 0.05 to 10 mM, e.g. from 0.05 to 5 mM.
• the temperature of the reaction mixture in the process of the invention will depend, inter alia, on the characteristics of the enzyme(s) employed and on the manner in which the process is carried out.
• the process is performed as a "one-stage" process in which lignocellulosic material, phenolic carboxylic acid, enzyme and oxidizing agent are all present together essentially throughout the process, it will normally be desirable to limit the upper temperature employed to a temperature which does not cause adversely rapid deactivation of, in particular, the enzyme employed. In such cases, the temperature will normally not exceed about 80°C, and will suitably be in the range of 20-70°C.
• the process of the invention in more than one stage, e.g. by first "activating" the lignocellulosic material and the phenolic carboxylic acid, respectively, using enzyme and oxidizing agent at a temperature as mentioned above (i.e. a temperature which is typically in the range of 20-80°C, such as 20-70°C), and then combining the activated lignocellulosic material and the activated phenolic carboxylic acid and - if appropriate - raising the temperature, e.g. to a temperature in the range of 70-170°C. This may require pressurization of the reaction vessel/system to prevent boiling of the reaction medium.
• the reactions involved in a typical process of the invention may take place satisfactorily at a temperature in the vicinity of ambient temperature (which is often about 25°C), such as a temperature of about 30°C.
• the pH in the reaction medium in which the process of the invention takes place will generally be in the range of 3-10, preferably in the range of 4-9, and often in the range of 4-8.
• reaction times employed in performing a process of the invention will depend, inter alia , on the temperature(s) employed, and the nature of the lignocellulosic material and the phenolic carboxylic acid employed; it is thus difficult to give general guidelines in this respect. As illustrated by a working example herein, the use of a temperature of about 30°C results in satisfactory reaction being achieved within a period of less than 1 hour.
• the present invention also relates to a modified lignocellulosic material, wherein the charge density of the lignocellulosic material is increased by attachment thereto of a carboxylic acid or a salt or an ester thereof.
• a modified lignocellulosic material according to the invention may (a) be isolated (as an intermediate product) and subsequently used as a starting intermediate for the preparation of a strengthened lignocellulose-based product of interest; or (b) subjected directly (i.e. without isolation) to those further process steps which are appropriate for the manufacture of the final strengthened product.
• a process of the invention as described above is well suited to the production of a variety of types of lignocellulose-based products, such as various paper products [for example writing and printing paper, paper bags, packaging paper (e.g. "brown paper” and the like)], paperboard products (such as cardboard, linerboard and the like), tissue and non-woven products, and a variety of other speciality products (e.g. egg boxes, egg trays and other types of packaging materials).
• various paper products for example writing and printing paper, paper bags, packaging paper (e.g. "brown paper” and the like)]
• paperboard products such as cardboard, linerboard and the like
• tissue and non-woven products e.g. egg boxes, egg trays and other types of packaging materials.
• lignocellulosic material as defined above
• another type of material notably fibre material
• an non-ligninaceous (non-phenolic) "activatable” functionality e.g. of the aromatic amine type
• the material need not comprise a cellulosic or hemicellulosic component, but may instead comprise some other component derived from another type of naturally occurring or synthetic polymer or copolymer.
• a solution containing the sodium salt of ferulic acid for use in the example given below was prepared as follows: 2.0 g of ferulic acid was suspended in 100 ml of de-ionized water. 4M aqueous NaOH was added slowly until all the ferulic acid had dissolved, at which point the pH of the solution was about 7.5.
• Example 1 Grafting of ferulic acid onto beech wood pulp
• a 20g portion of beech wood pulp was suspended in 1000 ml of de-ionized water.
• the pH of the suspension was adjusted to 4.5 by addition of 4M sulfuric acid, and was maintained thereafter between 4.5 and 6 throughout the subsequent procedure, described below, by addition of aqueous 4M sodium hydroxide or aqueous 4M sulfuric acid.
• the suspension was stirred, aerated by bubbling with air, and maintained at a temperature of 30°C by immersion of the vessel containing the suspension in a thermostatted water bath:
• laccase 3 LACU/g of pulp dry matter
• "ferulic acid” solution vide supra
• the total amount of solution added during the 15 minute period was equivalent to an amount of ferulic acid corresponding to 2% w/w of the pulp dry matter.
• reaction mixture was filtered by suction on a Büchner funnel.
• the solid material on the filter (modified beech pulp) was resuspended in water to give a concentration of suspended solid of ca. 1% w/w, and the suspension was suction-filtered as before.
• the surface charge of the four pulp samples was determined by polyelectrolyte adsorption experiments with PolyDADMAAC (a cationic polymer) according to the procedure described by L. W ⁇ gberg et al., Nordic Pulp Pap. Res. J. 4(2) (1989) 71.
• an appropriately charged strengthening agent e.g. a cationic starch in the case of a charge-conferring substituent which gives rise to a negative charge, such as carboxyl (-COOH ⁇ -COO - )] into a lignocellulose-based product (e.g. a paper product) during preparation of such a product starting from a modified lignocellulosic material according to the invention, whereby increased strength of the lignocellulose-based product (e.g. increased tensile strength, tear strength and/or compression strength in the case of a paper product) may be achieved.
• an appropriately charged strengthening agent e.g. a cationic starch in the case of a charge-conferring substituent which gives rise to a negative charge, such as carboxyl (-COOH ⁇ -COO - )
• a lignocellulose-based product e.g. a paper product
• increased strength of the lignocellulose-based product e.g. increased

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• 1997
  • 1997-02-07 ES ES97901525T patent/ES2171880T3/es not_active Expired - Lifetime
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  • 1997-02-07 DE DE69710046T patent/DE69710046T2/de not_active Expired - Lifetime
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• 1998
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